Information accessed by a computer system is often preserved for later retrieval by the computer system. In some circumstances, a computer system prevents access to a particular file stored on a disk when writing information (e.g., transactional information) to that file until such writing completes. This occurs to avoid corrupted transactions. For example, a database management system (DBMS) generally requires that all updates to files stored in non-volatile storage (e.g., a disk) are completed before that file is made available for access by an application.
In particular, a “database commit” is the final step in the successful completion of an update to a file made as a part of handling a transaction. For example, when a single transaction includes several steps, then all of the steps must be completed before the transaction is deemed successful and the database file is actually changed to reflect the transaction. When a transaction completes successfully, the changes to the file are said to be “committed”.
Since a read or write transaction requires a read from or a write to non-volatile storage (e.g., disk) and access to the disk is limited until the previous transaction is committed, access to the database file is slowed by the delays in committing the data. Consequently, the performance of the DBMS decreases.
One prior art solution to this problem is to store the information in a temporary log file in volatile cache memory so that the DBMS can commit the information to disk at a later time. Further, the performance decrease of the computer system when writing the information is typically reduced when the information is first written to the log file rather than non-volatile storage (e.g., disk). However, if the computer system failures (i.e., crashes) before the computer system updates the disk with the data updates stored in the volatile cache memory, all update information stored in the volatile cache memory is deleted and typically irretrievable.
Thus, there remains a need to store transactional information in a manner that allows the information to be available following a computer system failure without having to perform the same transaction again. Additionally, there remains a need to have the transactional information available after a system failure in a more efficient manner than currently available.